kaizen: add equals-ignore-case pattern

[timbray]

addresses: #186

This adds support for the equals-ignore-case pattern. The automaton-building is a bit complex but reasonably well tested.

What is controversial is that this PR contains Quamina's first generated code - the case-mappings are pulled from the file CaseFolding.txt in the Unicode Character Database. The generated code is in case_folding.go. It is built by code_gen/build_casefolding_table.go which is in package main and has main()

The problem is that the CaseFolding.txt is regularly changed with Unicode releases. So build_casefolding_table checks to see if the case_folding.go file is older than 3 months and if so, rebuilds it. There is a Makefile to take care of building and running the code generator. So if you're doing a PR you should at some point type make and if you get a new case_folding.go then check it in with your PR.

There are a couple of problems. First, I've never done generated-Go code before and maybe there's a much better well-known approach. Second, I haven't figured out how to unit test the code generator. The coverage tools ignore it because it's not in the quamina package. Implicitly, it's tested by the tests in monocase_test.go and elsewhere having the desired results but I'm going to open an issue to figure out how to test properly.

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 97.50000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 96.59%. Comparing base (8da5067) to head (0a03480).

Files	Patch %	Lines
monocase.go	96.07%	1 Missing and 1 partial ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #340      +/-   ##
==========================================
+ Coverage   96.56%   96.59%   +0.03%     
==========================================
  Files          18       19       +1     
  Lines        1863     1940      +77     
==========================================
+ Hits         1799     1874      +75     
- Misses         36       37       +1     
- Partials       28       29       +1     

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[timbray]

Hmm, surprised by the benchmark failures, I didn't think I changed anything that should affect an existing benchmark. Will investigate. Could be trailing fallout from the Q-numbers work.

[arnehormann]

@timbray Go itself (the x package is semi-official and comes close to the standard library) appears to do it this way:
https://cs.opensource.google/go/x/text/+/master:gen.go
with generated code like this: https://cs.opensource.google/go/x/text/+/master:cases/tables15.0.0.go

[timbray]

This is annoying; the same problem with the same benchmark showed up on the Q numbers PR, and I accepted the numeric-match slowdown in the interests of correctness. So I changed the CI/CD to warn but not fail, and then after everything was clean I put the CI/CD back to fail mode, assuming that would reset the cached previous value. Apparently this did not happen; I have poked around and failed (so far) to figure out how/where the benchmark tool caches previous results.

Anyhow, for now, I'm going to reset the CI/CD again not to fail on slowdown.

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Go Benchmark'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.20.

Benchmark suite	Current: 0a03480	Previous: 78e2ec8	Ratio
BenchmarkCityLots	6894 ns/op 830 B/op 34 allocs/op	5592 ns/op 773 B/op 31 allocs/op	1.23
BenchmarkCityLots - ns/op	6894 ns/op	5592 ns/op	1.23
Benchmark_JsonFlattner_Evaluate_ContextFields	1247 ns/op 96 B/op 8 allocs/op	726.2 ns/op 56 B/op 4 allocs/op	1.72
Benchmark_JsonFlattner_Evaluate_ContextFields - ns/op	1247 ns/op	726.2 ns/op	1.72
Benchmark_JsonFlattner_Evaluate_ContextFields - B/op	96 B/op	56 B/op	1.71
Benchmark_JsonFlattner_Evaluate_ContextFields - allocs/op	8 allocs/op	4 allocs/op	2

This comment was automatically generated by workflow using github-action-benchmark.